<HTML
><HEAD
><TITLE
>The root filesystem</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.63
"><LINK
REL="HOME"
TITLE="The Linux System Administrator's Guide"
HREF="index.html"><LINK
REL="UP"
TITLE="Overview of the Directory Tree"
HREF="dir-tree-overview.html"><LINK
REL="PREVIOUS"
TITLE="Background"
HREF="x264.html"><LINK
REL="NEXT"
TITLE="The /etc directory"
HREF="x399.html"></HEAD
><BODY
CLASS="SECT1"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="NAVHEADER"
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>The Linux System Administrator's Guide: Version 0.7</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="x264.html"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
>Chapter 4. Overview of the Directory Tree</TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="x399.html"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN319"
>4.2. The root filesystem</A
></H1
><P
>The root filesystem should generally be small, since
	it contains very critical files and a small, infrequently
	modified filesystem has a better chance of not getting corrupted.
	A corrupted root filesystem will generally mean that the system
	becomes unbootable except with special measures (e.g., from a
	floppy), so you don't want to risk it.</P
><P
>The root directory generally doesn't contain any files, except
	perhaps the standard boot image for the system, usually called
	<TT
CLASS="FILENAME"
>/vmlinuz</TT
>.  All other files are in 
	subdirectories in the root filesystems:

	<DIV
CLASS="GLOSSLIST"
><DL
><DT
><B
><TT
CLASS="FILENAME"
>/bin</TT
></B
></DT
><DD
><P
>Commands needed during bootup
		that might be used by normal users (probably after
		bootup).</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/sbin</TT
></B
></DT
><DD
><P
>Like <TT
CLASS="FILENAME"
>/bin</TT
>, but the
		commands are not intended for normal users, although they
		may use them if necessary and allowed.
		<TT
CLASS="FILENAME"
>/sbin</TT
> is not usually in the default
		path of normal users, but will be in root's default
		path.</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/etc</TT
></B
></DT
><DD
><P
>Configuration files specific to the
		machine.</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/root</TT
></B
></DT
><DD
><P
>The home directory for user root.  This is
		usually not accessible to other users on the
		system</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/lib</TT
></B
></DT
><DD
><P
>Shared libraries needed by the programs on
		the root filesystem.</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/lib/modules</TT
></B
></DT
><DD
><P
>Loadable kernel modules, especially those
		that are needed to boot the system when recovering from
		disasters (e.g., network and filesystem
		drivers).</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/dev</TT
></B
></DT
><DD
><P
>Device files.  Some of the more commonly
		used device files are examined in <A
HREF="device-list.html"
>Chapter 5</A
>
		</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/tmp</TT
></B
></DT
><DD
><P
>Temporary files.  Programs running after
		bootup should use <TT
CLASS="FILENAME"
>/var/tmp</TT
>, not
		<TT
CLASS="FILENAME"
>/tmp</TT
>, since the former is probably on a
		disk with more space.  Often /tmp will be a symbolic link to
		/var/tmp.</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/boot</TT
></B
></DT
><DD
><P
>Files used by the bootstrap loader,
		e.g., LILO.  Kernel images are often kept here instead
		of in the root directory.  If there are many kernel
		images, the directory can easily grow rather big, and it
		might be better to keep it in a separate filesystem.
		Another reason would be to make sure the kernel
		images are within the first 1024 cylinders of an IDE
		disk.

		        <A
NAME="AEN375"
HREF="#FTN.AEN375"
>[1]</A
>
			
	       </P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/mnt</TT
></B
></DT
><DD
><P
>Mount point for temporary mounts by
		the system administrator.  Programs aren't supposed to mount
		on <TT
CLASS="FILENAME"
>/mnt</TT
> automatically.
		<TT
CLASS="FILENAME"
>/mnt</TT
> might be divided into
		subdirectories (e.g., <TT
CLASS="FILENAME"
>/mnt/dosa</TT
> might
		be the floppy drive using an MS-DOS filesystem, and
		<TT
CLASS="FILENAME"
>/mnt/exta</TT
> might be the same
		with an ext2 filesystem).</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/proc</TT
>,
	<TT
CLASS="FILENAME"
>/usr</TT
>, <TT
CLASS="FILENAME"
>/var</TT
>,
	<TT
CLASS="FILENAME"
>/home</TT
></B
></DT
><DD
><P
>Mount points
	for the other filesystems.

	        <A
NAME="AEN395"
HREF="#FTN.AEN395"
>[2]</A
>

	</P
></DD
></DL
></DIV
>
	</P
></DIV
><H3
CLASS="FOOTNOTES"
>Notes</H3
><TABLE
BORDER="0"
CLASS="FOOTNOTES"
WIDTH="100%"
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN375"
HREF="x319.html#AEN375"
>[1]</A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>This 1024 cylinder limit is no
			longer true in most cases.  With modern BIOSes and
			later versions of LILO (the LInux LOader) the 1024
			cylinder limit can be passed with logical block
			addressing (LBA).  See the <B
CLASS="COMMAND"
>lilo</B
>
			manual page for more details.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN395"
HREF="x319.html#AEN395"
>[2]</A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Although <TT
CLASS="FILENAME"
>/proc</TT
> does not
		reside on any disk in reality.  See the section about
		<TT
CLASS="FILENAME"
>/proc</TT
> later in the
		chapter.</P
></TD
></TR
></TABLE
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="x264.html"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="x399.html"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Background</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="dir-tree-overview.html"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>The <TT
CLASS="FILENAME"
>/etc</TT
> directory</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>